Is it possible to expose report or dashboard data embedded into visualforce page and place it in Public force.com site? If this is not possible then please provide me an example to build a custom report using analytics api/d3js/google charts and place it in public force.com site
It's definitely possible, but you have to watch out for licensing discussions. You might need Customer Community licenses to be able to do this.
You might find this post interesting.
yes, it is possible to show report and dashboard to a site. we can do so by either using customer community or partner community license. you have to do some additional stuff with this 1. creating community. 2. adding the tab of report and dashboard to a community. 3. Rules for the record type.